A plurality of top jaws radially equi-distant from one another and mounted on the face of a chuck for securing a workpiece in position for turning or cutting action thereon is well known in the art. The important and essential factor in almost all machining applications is the secure holding or gripping of the workpiece on which machining operations are to be performed. Top jaws themselves have been machined to grip the workpiece, but then discarded when that sized and configured workpiece has been machine-finished. U.S. Pat. No. 3,679,221, teaches the use of an insert, however, it is limited in its construction and use. The present state-of-the-art teachings do not disclose a rotatable, reshapeable insert or "slug" combined with a top jaw to achieve one or more of the objects described hereinafter.
One of the most commonly used tools for holding a part or workpiece is a turning chuck. This tool uses two or more manually-mounted top jaws on master jaws which make the holding or gripping of the workpiece possible.